1. Field of the Invention
The present invention relates to fluorinated benzaldehydes, to a process for preparing them and also to the use of the fluorinated benzaldehydes for preparing active ingredients, especially in medicaments and agrochemicals.
2. Brief Description of the Prior Art
Fluorinated benzaldehydes, for example fluorinated 2-hydroxy- and 2-alkoxybenzaldehydes, are valuable starting materials for the preparation of active ingredients in medicaments and agrochemicals. Their the fluorine or fluorinated substituents increase the lipophilicity and therefore the ability of the entire active ingredient molecule to pass through membranes. For example, compounds such as 5-fluoro-2-hydroxybenzaldehyde are suitable as the starting material for preparing medicaments which are used for treating cardiovascular diseases (see also WO-A 01/19780, p.81).
Of particular concern here are the methods of preparing fluorinated benzaldehydes and the attendant disadvantages are described as follows. Illustratively, 5-fluoro-2-hydroxybenzaldehyde can be prepared, for example, by formylating 4-fluorophenol (Suzuki et al., Chem. Pharm. Bull. 1963, 31(5), 1751-1753). However, the yields at less than 20% of theory are not acceptable.
There is therefore a need to provide fluorinated 2-hydroxy-3-methylbenzaldehydes and an efficient process for the preparation thereof.